Contrast agents can be used in a medical ultrasound examination to enhance diagnosis. The rate of contrast agent enhancement of tissue relates to the rate of blood flow to the tissue and can be used to diagnose a variety of disease states. While contrast agent quantification can be performed over an entire heart cycle, techniques have been discussed for performing quantification on specific parts of the heart cycle. For example, U.S. Patent Application Publication No. US2003/0114759A1 to Skyba et al. describes an ultrasonic imaging system and method for displaying tissue perfusion and other parameters varying with time in which gated or ungated images are used to enable a parametric display to be keyed to specific phases of the heart cycle. Additionally, QLAB Software by Philips Medical Systems has been described as containing custom tools to “auto trim” relative to an ECG trigger for quantification of specific parts of a cardiac cycle.